Compliant Actuator for Marine Vessel Hull Components
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Solution Overview
Problem
Existing actuators for seagoing vessels are prone to damage from opposing forces such as hydrodynamic and impact forces due to their rigid design, which can limit their operational effectiveness and reliability.
Innovation Solution
A compliant electric linear actuator with a stator and actuation member that yields to opposing forces exceeding a selected threshold, allowing the actuator to retreat while maintaining control force, thereby reducing the risk of damage and incorporating sensors and a transmission system for real-time force detection and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a rigid mechanical or hydraulic actuator is used to provide significant control force, then the actuator can overcome hydrodynamic forces and precisely control heavy control surfaces, but the actuator is prone to damage from opposing forces such as impacts and hydrodynamic loads
Solution Approach 1:
The actuator transitions from a rigid static structure to a dynamic compliant structure that can adapt its stiffness in real-time. The compliant mechanism allows the actuator to yield to impact forces while maintaining control authority during normal operation, resolving the contradiction between providing sufficient control force and resisting damage from opposing forces
Solution Approach 2:
The actuator changes its mechanical parameter (stiffness) based on operational conditions. During normal operation, the actuator maintains high stiffness for precise control, but during impact events, it transitions to a compliant state with reduced stiffness to absorb impact energy, thereby preventing damage while maintaining control capability
2Reliability
If the actuator is designed to be compliant and yield to opposing forces, then damage from impacts is mitigated, but the actuator may lose control precision and positional accuracy
Solution Approach 1:
The actuator incorporates sensors that provide real-time feedback on its position, force, and compliance state. This feedback enables the control system to maintain precise control by actively compensating for the compliant behavior, ensuring that the actuator yields to impacts while returning to or maintaining its commanded position with high accuracy
3Force
If traditional mechanical locking mechanisms are used to maintain position, then holding force is sufficient, but the actuator cannot adapt to varying opposing forces and is vulnerable to impact damage
Solution Approach 1:
The actuator replaces static mechanical locking with a dynamic compliant mechanism that can continuously adapt to varying opposing forces. The compliance mechanism allows the actuator to maintain contact and control while yielding to forces beyond its control capacity, providing both holding force and adaptability to different operational conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The actuator effectively mitigates damage from opposing forces by reducing unbalanced forces and accelerations, ensuring precise control and extended operational lifespan of vessel components.
Implementation Method 1
an actuation member (18) adapted for linear movement in response to an electro-motive force resulting from current flow in the stator (16)
Data Source
Figure 1~2
Figure 3~4
AI summary
An actuator (10) for use in controlling movement of a component (22) of a seagoing vessel comprises a cylinder (12) for coupling to a vessel hull (14) and an actuator shaft (18). A distal end (20) of the shaft (18) is coupled to the component whose movement is to be controlled and, in use, a control force (Fc) is applied to the shaft (18) to control movement of the shaft (18) from a first position, retracted, position to a a second, extended, position. The actuator (10) is compliant in response to an opposing force exceeding a selected force to prevent or mitigate damage to the component (22) and/or the actuator 10 which may otherwise result from the opposing force.